The purpose of this study is to determine if lack of glucagon suppression causes postprandial hyperglycemia in the presence of impaired insulin secretion in subjects with type 2 diabetes mellitus. Eight subjects with type 2 diabetes mellitus have been studied on two occasions. On both occasions volunteers received a 50g glucose drink while their endogenous hormone production was inhibited by somatostatin. Insulin was infused to mimic a diabetic postprandial profile. Glucagon was infused at a rate of 1.25 ng/kg/min beginning either at time zero to prevent a fall in postprandial glucagon concentrations or beginning at two hours so as to create a transient fall in plasma glucagon concentrations.